Method for producing lubricating oil



June 25, 1935.7. u. B. BRAY METHOD FOR PRODUCING LUBRICATING OIL FiledJan.- 26, 1955 2 Sheets-Sheet 1 uzEomm L wmwzwazou 20 Q HHMKNWIF wm%\ v.HZK ON "Area KNEE @E A &

n54 uammnsw l W VK June 25, 1935. u. B. BRAY METHOD FOR PRODUCINGLUBRICATING OIL 2 Sheets-Sheet 2 Filed Jan. 26, 1955 MMH 240mm PatentedJune 25, 1935 2,000,095 ms'rnon roa PBOgIIJLCING LUBBICATING UNITEDSTATES PATENT OFFICE Ulric B. Bray, Palos Verdes Estates, CaliL, as-

signor to Union Oil Company of California, Los Angeles, Gaii1'., acorporation of California Application January 26, 1935, Serial No. 3,61315 Claims. ('01. 190-34) This invention relates to the production oflublbs. The extraction of the oil from the asphalt at ricating oils fromcrude oils containing asphalt such pressures results in an asphaltsubstantially and wax and is a continuation in part of my free of oiland a solution of oil in the liquid peapplication Serial No. 486,724,filed October 6, troleum fraction. This solution contains subtan- 51930, and a continuation in part ofmy applicatially all the wax present.in the crude oil. 6

tion Serial No. 694,839, filed October 23, 1933, It has also beenfoundthat oil containing aswhich was divided'from my application Serial No.phalt and impurities such as wax may be first 466,189 filed July 7,1930. freed from the asphalt by a primary extraction This invention isdescribed but not claimed in with a light solvent such as the solventdescribed 10 my copending applications Serial No. 597,419 filed aboveand that the impurities such as wax, may 10 March 7, 1932 Serial No.625,562 filed July 29, then be removed at a suitable temperature by the1932;v Serial No. 625,563 filed July 29, 1932; Serial aid of a heaviersolvent, such as naphtha in which No. 650,995 filed January 10,. 1933;Serial No. the wax is substantially insoluble at the low tem- 693,644filed October 14, 1933; Serial No. 707,641 perature employed. By heaviersolvent, I mean is filed January 22, 1934; Serial No. 707,642 filed oneof high r ilin point than th li t s lvent 10 January 22, 1934; SerialNo. 721,602 filed April previously described.

20,-1934; and Serial No. 749,649 filed Oct. 23 1934. Advantage is takenof the high volatility of the The invention is also described but notclaimed in l ht olvent to cause a cooling of the oilupon a my Patents1,944,491 and 1,949,989 which are also release of pressu e to producethe p ion of divisions of my copending application Serial No. thecontained wax. A further advantage in cool 20 4 ,139 filed July 7, 1930,1 ing the oil in this manner is to bring the oil to a It has beendiscovered that superior lubricating p op r temperature for acidtreatment. 3? acid 11 and asphalts can be obtained from crude 11-treatment, I intend toinclude treatment with by causing separation ofthe lubricating oil from acid followed by the p o neutralization and/or25 the asphalt at temperatures below that at which y treatment. 1 i

i deleterious changes are induced in the'oil. 1 I1 alarge p p rtion ofthe Pr 18 It has been found that if oil containing asphalt ved from thes u on after the asphalt has is heated-in the presence of the asphalt,the latter been separated, the rema t o becomes catalyzes certainreactions in the oil which result too us a d not of sufllciently lowspecific in the destruction of those characteristics of the gravity toPermit Satisfactory avio in the 80 lubricating oils which are mostdesirable. dewflxing p at hich is conveniently accom- It has been foundadvisable to cause the sepp ed in a centrifuge. Difllculti. are also*aration of asphalt from the oil by means of volate d n ca y reat ls ofhi tile solvents which are capable of dissolving the Viscosityy ve navoids these difllculties oil and any wax and which do not dissolve theby mixing the oil with naphtha before W S. 35

asphalt. Such solvents are light petroleum fracto reduce the Viscosityand Place the oil in P p tions, such ascasinghead gasoline and naphthacondition for downing The reduced s ty and also petroleum fractionsnormally vaporous is also advantageous in c mical treatment of atordinary temperatures and pressures. Other the If p is expanded at y w De 40 solvents which may be used are alcohol, ether, Sure into the oilPrior to downing, it may a so 40 mixtures of alcohol and ether, acetone,etc. I have a cooling eiieot Similar to that a ed, by prefer to. use asour volatile solvent a petroleum expansion of the p Y ap a. I fractionobtained by the rectification of natural meonthose Petroleum fractions wch Vary from gasoline. The fractions are composed in the main keroseneto light fractions of gasoline, preferably of propane and isobutane. Atypical analysis of a gasoline-like fraction having 8 p fic r vity 45such a fraction is 6.72% ethane, 72.2% propane f a o t and boiling rangeof about and 19.91%.isobutane and 1.17% normal butane. ZOO-300 F.Instead of naphtha I may use other It will be understood, however, thatthese merely solvents or diluents, for in l. a coho s illustrate thetype of traction used and the comsuch as methyl, ethyl, propyl; -butylalcohol or 50 position may vary. mixtures of the same, ketones such asacetone or 50 In order to cause the extraction with this liquid di-ethylk chlorinated light hydrocarbons fraction, the solution is maintained ata pressure such as dichlorethylene. trichloret y n the suflicient tomaintain the propane liquid at ordilike, or mixtures of benzol withacetone or other nary temperatures. The fraction above describedketones, or mixtures of benzol and butanol or is liquid at ordinarytemperatures at about other alcohols.

In addition to the power which the naphtha has of reducing the viscosityof the asphalt-free oil, it also is used as an extracting medium for waxor other material whose presence is deleterious in a finished, highgrade lubricating oil. The naphtha, it used in sufllcient quantities,acts as a solvent for the oil during the removal of the wax or otherimpurities in a manner similar to the action of the propane solutionduring the removal of -the asphalt. By regulating the quantity,substantially oil-free wax may be precipitated. In comparing theirvolatility and specific gravity, the propane is considered to be thelight solvent and the naphtha is the heavier solvent. An advantage inusing both light and heavy solvents resides in the fact that thedewaxing may take place in the presence of the heavier solvent after thelighter, more volatile solvent has been evaporated with a consequentdecrease in the temperature of the wax-containing oil.

It is, therefore, an object of my invention to produce lubricating oilfrom oil containing asphalt and impurities by extracting the lubricatingoil first with a light solvent, such as propane, to precipitate theasphalt and then extracting the oil from the impurities such as wax,with a heavier solvent such as naphtha.

It is a further object to produce lubricating oil from the oil describedabove by maintaining pressure on the oil and light solvent during theextraction of the asphalt and to extract the impurities such as wax fromthe asphalt-free oil by means of a heavier solvent under reducedpressure.

It is furthermore an object of my invention to produce lubricating oilfrom oil containing asphalt and wax, by mixing this oil with a solventin which the lubricating oil fractions and wax are soluble, but in whichthe asphalt is insoluble, and subsequently separating the wax from thelubricating oil fractions in the presence of naphtha.

It is a further object of this invention to mix the naphtha with the oileither in the presence of substantially all the propane used toprecipitate the asphalt, or in the presence of only a portion of saidpropane, or the naphtha may be added after substantially all the propanehas been separated from the oil and wax.

It is a further object of this invention to produce lubricating oil fromoil containing asphalt and wax by precipitating the asphalt with asolvent for the oil and wax and to chemically treat the oil eitherbefore or after removal of the wax from the oil, and either before orafter the addition of naphtha to the oil and wax.

Another object of this invention is to produce lubricating oil from oilcontaining asphalt and wax by mixing a volatile solvent therewith underpressure to precipitate the asphalt and dissolve the lubricating oilfractions and wax, separate the precipitated asphalt under pressure, andtaking advantage of the highly volatile characteristics of the solventby releasing the pressure and allowing the solvent to vaporize andconsequently cool the oil and wax, thereby precipitating the latter, andto separate the wax from the oil in the presence of naphtha.

Another object of the invention is to produce lubricating oil in themanner described above and to make further use of the volatility of thesolvent by partially releasing the pressure on the oil, solvent and waxsubsequent to the removal of the precipitated asphalt under pressure,whereby the oil, wax and the solvent which remain in the liquid form aresufficiently cooled to be at the desired temperature for chemicaltreatment, and after chemical treatment, making use of the volatility ofthe remaining solvent by further releasing the pressure andprecipitating the wax due to the consequent cooling.

The process will be more adequately understood by reference to thedrawings which show preferred schematic arrangements of the apparatus tocarry out the process described herein.

Fig. l is a schematic arrangement of apparatus in which the oil is firstmade asphalt-free and then is chemically treated in the presence ofsubstantial quantities of solvent.

Figure 2 is a modification oi the schematic arrangement of apparatusshown in Figure 1.

Referring to Fig. l, topped residuum from tank 40 is passed by pump 4|through line 42 where it meets a propane solution of lubricating oilcoming through line 54. The propane and residuum pass through theturbulence or mixing coil 43 and then into decanter 44. The asphalt inthe residuum is precipitated by the propane and settles to the bottom ofdecanter 44. The precipitated asphalt resemblesa slurry and may be drawnoff from the bottom of the decanter with sufficient liquid propane topermit pumping.

The asphalt propane slurry is passed through line 45, pump 46 and line41 where it is mixed with fresh liquid propane from storage 48 sent viapump 49 and line 41. The mixture is then passed into mixing coil 50 andinto decanter 5|. If it is desired to produce an asphalt containingstill less oil or wax, the countercurrent washing with propane may beextended to as many steps as desired. Decanters 44 and 5| and storage 48are maintained at the same pressure by means of equilibrium lines 55controlled by valves 56. The pressures in 44, 5| and 48 are sufiicientto maintain the solvent in liquid state at ordinary temperatures.

The clear overflow from decanter 5| consisting of liquid propane inwhich is dissolved a small amount of oil is sent through line 52, pump53 and line 54 to its connection with line 42 where it is mixed with theincoming topped residuum. The mixed residuum and propane pass throughmixing coil 43 and into decanter 44 as described above.

The asphalt slurry from decanter 5| is drawn off through line I28 andpressure release valve I29.

The clear overflow from decanter 44, now consisting of a moreconcentrated solution of lubricating oil and propane, is next preparedfor acid and alkali treatment at reduced temperature. A reducedtemperature is very beneficial in the chemical treatment of certaintypes of oils. In order to lower the temperature of the propanesolution, the pressure on the solution is decreased to a valuecorresponding roughly to the vapor pressure of propane at the desiredtreating temperature and evaporation of the propane takes place untilthis temperature is reached, thepressure in the meantime being heldconstant by automatic pressure regulating valves. A temperature of about40 F. is desirable in the following chemical treatment and may beobtained by reducing the pressure on the propane solution tosubstantially 70 lbs. per square inch.

The propane solution from the top of decanter 44 is therefore passedthrough line 51 to the pressure release valve 58 and into expansionchamber 59 which is held at a predetermined pressure by means ofautomatic back pressure cooler ill.

The cooled propane solution in expansion chamber II is sent through line02 by pump 68 to turbulence or mixing coil 01 andthence to decanter ll.Sulfuric acid is introduced from tank I by means of pump It into lineit. The acid treated oil solution is decanted and the sludge is'withdrawn through line I. The oil is sent by line 10 and pump 1i intoturbulence or mixing coil I1 and thence to decanter ll. Water for use inwashing the acid treated oil is introduced in line II from water storageI2 via pump 13, valve llrand line it. The washed oil is then decantedand is removed from decanter ll via line ll and pump Ii into line If.The wash-water is removed from decanter I. through line It.

Alkali from alkali storage 81 is then admitted to line 82 via pump IIand line II. The oil and alkali flow through turbulence coil It intodecanter I! from which the alkali sludge is removed via line II. Thedecanted oil from I! is next sent into line fl by pump II and thenceinto turbulence coil 02. Wash water is also allowed to enter said coilIf by passage from water storage 12 via pump II. valve ll, line Ii andline II. From the turbulence coil If, the material passes into decanterOI from which the wash water is removed via l4. Pressure is maintainedon the decanters ll, ".11 and ",as above described.

The treated oil solution leaving the treating group by means of line IIis passed by pump I through a second expansion valve l'l where thepressure is released to that corresponding to the dewaxing temperature.This pressure will be substantially atmospheric and its correspondingtemperature will be about F. Then'the oil passes to expansion chamberili wherein propane is evaporated and retumed by line ill to storage ll.The oil, free of propane, leaves'by ill to a dewaxing operation and thento storage, not shown. If desired, naphtha may be added to theoil-propane solution prior to evaporating the propane to give sufficientfluidity during the removal of wax.

Since the separation of asphalt from the oil by distillation of the oilcannot be accomplished without destruction of the paraffin basecharacteristics of the oil, the process devised by me for removal of theasphalt comprises its precipitation by means of solvents. Asphalt may beprecipitated from oil by chemicals," such as sulfuric acid. I findhowever, that it is best precipitated by use of solvents in which thelubricating oil fractions are soluble but in which the asphalt isinsoluble. Such solvents are alcohol, ether, mixtures of ether andalcohol, acetone. volatile hydrocarbon solvents, such as casingheadgasoline and light naphthas. I find, however, that the process is bestcarried out by the use of hydrocarbons which are normally in the vaporstate at atmospheric pressure and temperature. Such hydrocarbons includepropane, isobutane, butane, ethane, methane and mixtures thereof. Thesemay be obtained by rectification of casinghead gasoline by the so-calledstabilizing method now conventional in the natural gas industry. Theyare the overhead thus obtained. They are liqueiled by compression andcooling in the conventional manner and drawn 01! into pressure chamberswhere they are maintained in the liquid state until they are used. Atypical analysis of such a fraction is 6.72% ethane, 72.20% propane,19.91% isobut'ane and 1.17% normal butane and the necessary pressure tomaintain the fraction in a liquid state is approximately 125 lbs. persquare inch gauge at 73 F.

The oil stock containing asphalt is mixed with this liquid solvent undersuperatmospheric pressure and the mixture is allowed to settle to permitthe precipitation of the asphalt. The solution of lubricating oil in theliquid solvent is withdrawn from the pressure precipitator and expandedthrough heating coils to vaporize the solvent, leaving behind the liquidlubricating oil free of asphalt. The vapors are recompressed and cooledto liquefy them and are then returned to the system. The lubricating oilfraction produced may then be distilled at atmospheric pressure byconventional methods of distillation. such as the tube still or theshellstill with proper rectification or fractionating equipment toproduce any desired cut of lubricating oil.

'Any contained wax may be extracted and the oil treated with acid. Iprefer to distill the oil to leave a residue which contains thefractions having a viscosity above 400 to 500 seconds Saybolt Universalat 100 F. In other words, the

degree of distillation should leave a residue such that if it wereredistilled the first fractions taken overhead would be about 600 to 800seconds Saybolt Universal at 100? I". These figures are by their verynature approximate since they must overlap and the spread of the cutwill be dependent on the percentage taken overhead. This will result ina minimum deterioration of the desirable temperature viscositycharacteristics. Obviously, the oil may be more deeply topped, i. e.higher viscosity oils may be taken overhead if a partial sacrifice ofthose desirable qualities is not uneconomic. It is to be noted that theabove criteria will hold both for batch and for flash distillationwithin reasonable commercial limits. It is preferred to top the crude soas to leave behind a residue which on extraction, as above, leaves alubricating oil of the desired viscosity. However, the process may berun as well by topping the crude as far as possible, i. e. withoutinjuring the paraffin base characteristics, extracting the residue toremove the asphalt, treating the distillate and residue with acids.alkali and/or clay and then blending to the desired viscosity.

The following is a description of a preferred method for treating amixed'base oil, 1'. e., one containing asphalt and wax, wherein theasphalt is precipitated under conditions such as to leave the wax andoil in the propane solution. Advantage is taken of the propane solutionto permit a continuous acid treatment and alkali treat ment of the oil.This is a particular advantage of this process since it permits rapidsettling of the-sludge. The extreme volatility of the propaneis used to'act as a refrigerant to cause separation of the wax. The process willbe more particularly described by reference to Fig. 2.

The modification shown in Fig. 2 is described in my copendingapplication, Serial No. 694,839, filed. October 23, 1933, of which thepresent application is a continuation in part.

Referring to Fig. 2, topped residuum stored in tank 31 is sent by pumpll, and meets liquid propane containing a small amount of oil comingthrough line 4|. The preferred fraction is that obtained as an overheadin the stabilization of natural gas gasoline. The mixture of propane andresiduum pass through mixing coil 39' into decanter 40', where theasphalt in the topped residuum is precipitated and settles rapidly as aslurry. From the bottom of decanter 40', the asphalt slurry is pumped bypump 4| to meet fresh liquid propane introduced by pump 46 via line 41'from propane storage 48'. The asphalt slurry and-fresh liquid propaneare sent through mixing coil 42' into decanter 43. The asphalt propaneslurry from the bottom of decanter 43' is drawn off through line I45 forrecovery of asphalt and propane.

The overflow from decanter 43', containing the oil and wax is sent bypump 44' through line 45' to be mixed with the topped residuum and sentinto decanter 40', as explained above. The overfiow from decanter 40'consisting of propane and lubricating oil stock, in the desired ratio issent through pump 5| for the acid and alkali treatment of the extractedlubricating oil stock. The countercurrent washing of the precipitatedasphalt illustrated by the above method of operation may be extended toas many steps as desired, but in'general two decanters giving twocountercurrent washings will be sufllcient to produce an asphaltsatisfactorily free of wax and oil.

To the propane solution of extracted lubricating stock, acid from tank52' is added to mixer by means of pump (or acid egg) 53, and the fiow iscontrolled also by valve 54'. The propane solution and acid are forcedby pumps 5| and 53 through mixing coil 55' into decanter where the acidsludge settles rapidly. The addition of the acid in several dumpswithout drawing-*the sludge between dumps may be accomplished by tappingmixing coil 55' at various points and introducing acid at these points.The addition of acid in several dumps with the withdrawal of sludgebetween dumps may be accomplishedby means of additional mixing coils andacid decanters. The acid treated oil solution from decanter 60 flowscontinuously through line 62' into decanter 53', where water isintroduced as a spray through line 68' from water storage 64' throughpump 65' and valve 61' and acid reaction products are withdrawn throughline 58' controlled by valve 51'. The water washed oil overflows fromdecanter 63 and is sent by pump 69' to be treated. Water is withdrawnvia line 58' controlled by valve 59'. The soda solution contained intank I0 is introduced by pump 'Il' through line 12' controlled by valve"f. The mixture 01' oil solution and aqueous alkali solution is forcedthrough mixing coil 14' into decanter 15 where the caustic solutionseparates from the propane solution of the oil, and is withdrawn throughvalved line I6. The overflow from decanter 15 goes through line H todecanter 18', where water is introduced through spray 19' by means ofpump 65' through valve 66. The separated water wash is withdrawn throughvalved line 80. The use of propane as a solvent permits the continuousand rapid treatment of lubricating stock in the manner just described.

The neutralized and water washed oil solution overflowing from decanterI8 is carried by line 8| to tank 82. The oil in 82 is then treatedwithdrawn through line 5'.

The above descriptions are merely illustrative of the mode of employingmy invention and are not to be construed as limiting as many variationswill appear to those skilled in the art within the scope of my inventionwhich I claim to be:

1. The process for the production of lubricat ing oil from an oilcontaining the same which comprises mixing said oil with a liquefiednormally gaseous hydrocarbon solvent under superatmospheric pressuresuiiicient to maintain said solvent liquid, treating said 011 dissolvedin said solvent with a mineral acid and separating said solvent from thetreated oil.

2. A process as claimed in claim 1 in which the liquefied normallygaseous hydrocarbon contains a major portion of hydrocarbons having lessthan four carbon atoms.

3. A process as claimed in claim 1 in which the liquefied normallygaseous hydrocarbon contains a major portion of hydrocarbons of lessthan three carbon atoms.

4. A process as claimed in claim 1 in which the liquefied normallygaseous hydrocarbon contains a major portion of propane.

5. A process as claimed in claim 1 in which the liquefied normallygaseous hydrocarbon is propane.

6. A process as claimed in claim 1 in which the liquefied normallygaseous hydrocarbon is a hydrocarbon selected from the methane series.

7. A process for the production of lubricating oil from an 011containing the same which comprises mixing said oil with a liquefiednormally gaseous hydrocarbon solvent under superatmospheric pressuresufllcient to maintain said solvent liquid, treating said oil dissolvedin said solvent with sulphuric acid, and separating the solvent from thetreated oil.

8. A process as claimed in claim 7 in which the liquefied normallygaseous hydrocarbon is selected from the methane series.

9. A process as claimed in claim 7 in which the liquefied normallygaseous hydrocarbon is propane.

10. A process as claimed in claim '7 in which the liquefied normallygaseous hydrocarbon contained a major portion of hydrocarbons of lessthan four carbon atoms.

11. A process as claimed in claim 7 in which the liquefied normallygaseous hydrocarbon contains a major portion of propane.

12. A process as claimed in claim 1 in which the acid treated oil istreated with alkali.

13. A process as claimed in claim 7 in which the acid treated oil istreated with alkali.

14. A process as-claimed in claim 7 in which the lubricating oil mixedwith the liquefied normally gaseous hydrocarbon is cooled prior totreatment with sulphuric acid.

15. A process as claimed in claim 7 in which the lubricating oil mixedwith the liquefied normally gaseous hydrocarbon is cooled by vaporizinga portion of the liquefied normally gaseous hydrocarbon under reducedpressure prior to treatment with sulphuric acid.

ULRIC B. BRAY.

